State Health Officials On Guard For West Nile

August 6, 2002|By Robyn Suriano, Sentinel Staff Writer

As Louisiana suffers the worst outbreak of West Nile virus since 1999, Florida health officials are watching and waiting -- and hoping that the mosquito-borne disease doesn't infect residents again this year.

Florida was a hot spot for West Nile activity in 2001, when the virus made its first appearance here with a dozen human infections. But the trouble this summer has shifted with a vengeance to Louisiana, Texas and Mississippi -- with 88 human infections among the three states so far.

Fifty-eight of the cases have occurred in Louisiana; four of the victims have died, and the governor has declared a state of emergency. He is asking for federal money to boost spraying for mosquitoes, which carry the virus and pass it to humans through bites.

No human cases of West Nile have been detected in Florida this year, but officials say people still need to be careful to avoid mosquitoes. Horses and birds have tested positive for the virus in 26 counties, including Orange, Osceola, Volusia, Lake, Seminole and Brevard.

Once the virus has infiltrated a region, officials say it remains an ongoing threat. Most human cases last year were contracted in August and September.

"We're going into the peak season, so I think it's very important that we remain vigilant," said Dr. Steven Wiersma, state epidemiologist with the Florida Department of Health in Tallahassee. "It's impossible to say what kind of year it's going to be for us. We have such a short history with this disease, we just don't know, and that's a little bit frightening."

SPREAD OF VIRUS EXPECTED

Nationwide, the Centers for Disease Control and Prevention reports that West Nile has been found in 34 states and Washington, D.C., where a dead crow picked up from the White House lawn tested positive.

CDC officials say the spread of the virus is expected. West Nile circulates among birds, which carry it to new areas through migration. Mosquitoes pick up the virus by biting infected birds, then pass the infection to humans through subsequent bites. Horses also are susceptible to the disease.

Some types of birds -- crows and blue jays, for example -- usually die from the infection, and officials can track West Nile by testing dead birds. But most people who get bitten by a virus-laden mosquito do not become ill.

While urging caution, officials Monday also pushed for calm. They say people can protect themselves by taking standard precautions against mosquito bites: wearing repellent with DEET; staying indoors during peak mosquito time, from dusk to dawn; and clearing their properties of any standing pools of water that allow the insects to breed.

"I don't think we want to overstate the situation," said Dr. Julie Gerberding, CDC director in Atlanta. "There is a sense of urgency, but I don't think we need to send the message there's a crisis."

West Nile symptoms start with fever, body aches, headache and confusion. Older people are more at risk of serious infections that lead to encephalitis, a swelling of the brain that can cause death.

Before the recent deaths in Louisiana, the CDC had counted 185 confirmed human cases of West Nile and 18 deaths nationwide since 1999, when the virus first appeared, in New York. In 2001 alone, there were 66 cases of West Nile, including nine deaths. None of Florida's patients died.

But widespread horse and bird infections raised public awareness here last year. State laboratories were swamped with samples of dead birds that people found in their yards or neighborhoods.

Officials say they are not getting as many birds this year. Mosquito populations are not unusually high either, despite the almost-daily rainfall.

`PROACTIVE ACTION'

Orange County is seeing a lot of "nuisance mosquitoes" -- species that are vicious biters but not necessarily disease carriers, said Tom Breaud, manager of Orange County Mosquito Control.

Many counties, including Orange, keep flocks of sentinel chickens at various locations and test the birds weekly for West Nile or other viruses that cause encephalitis. Breaud said seven chickens have tested positive for West Nile so far, and two others have come back with Eastern equine virus.

"It's not anything yet for the epidemiology people to worry about because they are not clustered in time or space," Breaud said. "If we got 50 percent of the birds [with positive results] in one flock in one week, that would be a big deal."

Other counties throughout Central Florida are spraying as usual, responding to complaints from residents and targeting areas in which horses or dead birds have come back positive for the virus.

A positive bird was found recently in Oviedo, where officials have increased spraying around public schools, which open this week in Seminole County.

"Normally, we are complaint-based," Oviedo City Manager Gene Williford said. "Because of the positive tests, we've taken proactive action."

LOUISIANA'S CAMPAIGN

In Louisiana, where infections have taken off in recent weeks, officials have increased spraying and education efforts along with a campaign called "Fight the Bite." Not all counties -- or parishes, as they're called there -- have mosquito-control programs, said Kyle Viator, a spokesman for the Louisiana Department of Health and Hospitals.

Nevertheless, he said most of the human cases to date have occurred in regions where spraying is done. Officials say there is no real way to predict how West Nile will affect a region.

"Last year we had no data at all; this year we have a little bit," said Wiersma, the Florida state epidemiologist. "I think in 10 years we'll be much better equipped, but for now, we have to do the best we can with the data we have available -- and that's not much."